Gas turbine engines and other types of power generation equipment use a large volume of intake air to support the combustion process. Various types of inlet air filtration systems thus may be used upstream of the compressor. Impure air latent with dust particles, salt, debris, and other types of contaminants may damage the compressor blades, plug cooling passages, and damage other types of turbine components via corrosion, erosion, fouling, and the like. Such damage may reduce the life expectancy and performance of the gas turbine engine and other types of power generation equipment. To avoid these problems, the inlet air generally passes through a series of filters and screens to assist in removing the contaminants before they enter into the compressor.
One type of air inlet filtration system includes the use of a pulse filtration system. A pulse filtration system generally includes a number of pulse filters having a porous media filter element in communication with a source of compressed air. The pulse filtration system may be self-cleaning via a brief reverse pulse of the compressed air. The reverse pulse flexes the porous media filter element so as to dislodge the accumulated debris and other contaminants on the surface thereof.
The overall lifetime of the filters may be of concern, particularly in areas with high dust loading. Replacing the filters carries a cost in hardware, in material, as well as in lost power generation output. This reduced lifetime may be mitigated somewhat by the use of an oversized filter house. Such an oversized filter house, however, includes at least an initial increase in overall capital costs. Another issue may be that the pressure drop across the filters may increase over time as the filters collect dust and other types of debris thereon. As the inlet pressure drop increases, the overall output of the gas turbine engine may decrease. The cleaning efficiency of even a pulse filtration system thus may decay overtime as dust and other types of debris migrate into the filter media element. Eventually, the filters may need to be replaced to achieve the desired pressure drop thereacross.
Similarly, filter systems designed, for example, for coastal areas, may use filters for both dust and debris removal as well as for water removal. Water may combine with the dust so as to create pressure drop spikes. Given such, moisture separators/coalescing filters may be used. Multi-stage systems may be used with one system for dust and debris and a secondary system for water removal. Other systems may use a hydrophobic membrane laminated to the filter media or a hydrophobic media. Different types of oleophobic materials also may be used. These filters prevent free moisture from entering the compressor. The multi-stage filter systems, however, may be expensive and may cause an additional pressure drop. The laminated filters also may cause pressure drop spikes caused by fouling or water being trapped between the membrane and the base media. The hydrophobic media may be made from fragile glass fibers that may be damaged by pulsing.
There is thus a desire for an improved inlet air filtration system for use with pulse filters and the like and methods of use thereof. Such improved systems and methods preferably may avoid the accumulation of dirt, debris, and other types of contaminants without an increased pressure drop therethrough. Moreover, such improved systems and methods also may accommodate water removal. Overall system efficiency and performance also should be improved in a cost effective manner and with reduced overall downtime.